“Silicone is flexible and has good oxygen permeability,” said Hongjie Jiang, a post-doctoral researcher at the varsity.

“Laser machining helps us to tune that permeability and target just the wound site, which is hypoxic, rather than poison the rest of the foot with too much oxygen,” Jiang added.

In a paper published in the journal Materials Research Society Communications, the team said the insole can deliver oxygen at least eight hours a day under the pressure of someone weighing about 53-81 kg.

It can also be customised to take on any weight, the study said.

The team envisions a manufacturer sending a patient a pack of pre-filled insoles customised to his or her wound site, based on a “wound profile” obtained from a doctor’s prescription and a picture of the foot.

“This is mass-customisation at low cost,” said Vaibhav Jain, research associate at Purdue.

A patent is pending on the insole technology. The team is currently seeking corporate partners.